A signaling system has been developed in the field of railway industry. This system uses an interlocking device as a core of the protection system wherein a track circuit for detecting the train occupied position, a point device used for operation and locking of the point and a signal device for turning on the signal lamp to notify the operator of the permission or non-permission of entry of the train are interlocked to ensure that the train is prevented from entering the route where collision or derailment may occur.
As disclosed in Official Gazette of Japanese Patent hei 7 (1995)-41840, a technique has been developed in recent years, wherein the train position detected by an on-train apparatus is captured by radio, and the point device and signal device installed in the train are interlocked and controlled, based on this train position.
According to another technique having been disclosed in Japanese Patent Laid-open No. 2004-133585, the information on the position of a train is sent to other trains by radio, and the train is controlled, based on the position information sent by radio from other trains.